The present invention relates generally to retaining structures for overlapping sheets of material and, more particularly, to an apparatus for retaining first and second flaps of a storage box in a closed, overlapping condition.
It is well known that integral retaining or locking tabs can be used to retain overlapping flaps, such as in a box. Typically, rectangular tabs are hingedly coupled to a first flap by a folding line and thus defines a free end. A complementary aperture for receiving the tab is typically disposed on an overlapped second flap wherein the tab and aperture cooperate to retain the flaps in an overlapped condition. However, such a tab has a tendency to easily slip and thus disengage, allowing the flaps to become disengaged and pull apart.
It is further well known that if the tab has a shape slightly larger than or modified compared to the complementary aperture, the tab may be more securely held in its retaining condition. This has been accomplished by utilizing a rectangular aperture and a tab having a substantially trapezoidal shape. As such, the tapered edges of the trapezoid provide enhanced friction with the edges of the rectangular aperture due to their slightly larger size. However, a limitation of such a design is the added cost and complexity to manufacturing since separate die and punch processes must respectively be used for the flap and the aperture.